The present invention relates to an ivorylike composition plate for covering a wooden base and method for producing same, and more particularly relates to artificial material for covering a wooden base of a key of musical instruments having properties very close to those of natural ivory and its production.
Ivory has been highly appreciated by experts in the field of keyboard musical instruments such as pianos, organs and accordions as a material for composing at least surface sections of keys. Such preference for ivory is believed to be caused by, aside from the fact that ivory is a material well used for high class art objects, its ideal properties which suffice following requirements for materials to be used for production of keys for musical instruments.
(a) The material should have moderate moisture absorbability so that the key should well absorb sweat on the fingers of players in order to prevent undesirable finger slippage on the key during performance.
(b) The material should have moderate surface smoothness with moderate frictional resistance since these factors have a subtle influence on key touch.
(c) The material should have excellent appearance, i.e. high whiteness accompanied with high resistance against contamination.
(d) The material should have moderate hardness for better key touch and prevention of frictional abrasion even after long use.
(e) The material should have moderate workability for easy shaping into keys.
Poor supply of natural ivory having such ideal properties, however, cannot well meet the demand in the field of the musical instrument. In particular, African countries, which have long been a major and rich supply source of ivory, have started to ban or at least to impose severe restriction on collection of ivory in order to protect natural animals such as elephants.
In view of such a situation, synthetic resins have been widely used as a material for keys of musical instrument in recent years since they have no problem in constant supply. Synthetic resin keys, however, still have several drawbacks despite their beautiful appearance and flexible workability. That is, excessive smoothness of synthetic resin often causes undesirable finger slippage on keys, poor moisture absorbability of synthetic resin leads to sweat problem which may cause increased danger of finger slippage on keys, and relatively low hardness of synthetic resin eventuates in significant frictional abrasion of keys.
It is well known to produce so-called casein plastics by kneading and mixing casein with water after addition of any pigments or dyes, and hardening the mixture through treatment with formalin after molding. However, this sort of casein plastics also has some drawbacks when used for keys of musical instruments. Casein plastics lack in comfortable key touch, dimensional stability in dry and wet states, hardness, heat conductivity and massive impression of natural ivory.